Project Summary Breast reconstruction after tumor resection, traumatic wounds from war, and congenital defects often require a soft tissue filler to restore contour. Autologous adipose grafting has recently become the preferred standard of care for doctors because it is minimally invasive, limits chance of rejection, stems from a readily available source, and is inexpensive. Adipose also contains stem cells with the capability of differentiating into various cells needed for reconstruction. However, results of the procedure are unpredictable due to post-graft resorption caused by tissue necrosis. Up to 90% volume of the original volume can be resorbed 6 months post implantation. To address this critical issue, we plan to investigate the use of an injectable adipogenic hydrogel to enhance autologous fat graft survival. A decellularized adipose extracellular matrix will serve as the main polymer source for the hydrogel that also will contain dexamethasone-encapsulated microspheres to increase vascularization. The decellularized matrix will be fully characterized to demonstrate reproducibility of a material containing minimal cellular, DNA, and lipid content. Immunohistochemistry will determine protein content such as collagen, laminin, elastin, and other constitutive proteins. Dexamethasone-encapsulated microspheres will be placed in culture with peripheral bone marrow cells to determine bioactivity and in vitro release studies will determine drug discharge over time. Once the hydrogel is formed, cell culture studies with adipose derived stem cells will be conducted to access biocompatibility of the scaffold and its ability to differentiate the stems into adipocytes that produce lipids, representing its adipogenicity. An in vivo study using athymic mice as a small animal model will be the next step in the investigation. Liposuctioned adipose tissue will be processed and injected subcutaneously as a graft is prepared for patient undergoing autologous adipose graft treatment. These grafts are compared to a treatment group containing adipose tissue along with the injectable hydrogel and microspheres to observe volume retention and tissue histology after 3, 12, and 24 weeks. It is believed that the composite hydrogel scaffold will contain the necessary proteins and adipogensis biological factors to improve graft survival, which is desperately needed in the area of soft tissue reconstruction. Restoration of contour for patients with soft tissue defects is important for their emotional well-being, protection of underlying structure, and maintaining a normal human appearance.